R. Sivanandan

DEVELOPMENT OF MICROSCOPIC SIMULATION MODEL FOR HETEROGENEOUS TRAFFIC USING OBJECT ORIENTED APPROACH

Roads in India carry heterogeneous traffic with wide variations in static and dynamic characteristics of vehicles. The traffic flow is also generally devoid of lane discipline, with vehicles occupying any available road space ahead. Modeling of such heterogeneous traffic is generally complex in nature and simulation has been proven to be effective in studying such traffic. This paper presents the development of a model through object oriented programming (OOP) approach for simulating heterogeneous traffic. Several unique traffic characteristics have been considered in the modeling process. C++ language is used for this purpose. OOP leads to better structured codes for simulation and facilitates the development, maintainability and expandability of such codes. The first part of the paper explains the various logics of simulation such as vehicle generation, vehicle placement and vehicle movement. The second part of the paper describes the features of OOP, description of classes and class relationships. The last part of the paper presents the validation and advantages of the developed model.

Evaluation of Left Turn Channelization at a Signalized Intersection Under Heterogeneous Traffic Conditions

Abstract The behaviour of traffic in the heterogeneous environment of an urban signalized intersection is complex and difficult to model. This paper presents the development of a simulation model to imitate the flow of heterogeneous traffic through a signalized intersection. It discusses the validation of the proposed model in terms of queue density and dissipation of vehicles at an intersection approach and found to be satisfactorily replicating the field conditions. In this study, the model was extended to examine the effects of left turn channelization on vehicle waiting times. Sensitivity analysis was carried out to study the variation of vehicle waiting times. Analysis estimated that vehicle waiting times were reduced if a channelization was provided for a high traffic volume and certain proportions of left turn vehicles in the intersection approach. The length of channelisation has marginal impacts on vehicle waiting times.

Object-oriented methodology for intersection simulation model under heterogeneous traffic conditions

In developing countries like India, the traffic on roads is highly heterogeneous in nature, with vehicles of widely varying static and dynamic characteristics. In this type of traffic, vehicles do not follow lane discipline and they move freely over the entire width of roadway based on availability of space. To study this type of complex traffic flow and associated vehicular interactions, simulation is considered as an effective tool. An object-oriented methodology (OOM) for heterogeneous traffic simulation is proposed in this paper with focus on mid-block and intersection flow modeling. The paper presents the basics and advanced features of object-oriented programming (OOP) in detail in the context of traffic flow. The sample C++ code is discussed in detail to demonstrate the implementation of OOP features, such as encapsulation, inheritance and polymorphism. The contribution of this research work is the development of software objects for various components such as vehicle, traffic, link and node. This software can be adopted for heterogeneous traffic simulation programs, in general.

Study of traffic flow characteristics using different vehicle-following models under mixed traffic conditions

Abstract To understand the congestion problem and the occurrence of bottlenecks and to formulate solutions for it, a thorough study of vehicle-to-vehicle interactions is necessary. Car-following models replicate the behavior of a driver following another vehicle. These models are widely used in the development of traffic simulation models, and in analysis of safety and capacity. In India, traffic on roads is mixed in nature with wide variations in physical dimensions and other vehicular and traffic characteristics with loose lane discipline. In mixed traffic conditions, leader-follower vehicle types are not only car–car cases but also there are different combinations of vehicles (e.g. car-two wheeler, two wheeler-auto rickshaw, and heavy vehicle-two wheeler). The present study focuses on evaluation of different vehicle-following models under mixed traffic conditions. The car-following models such as Gipps, Intelligent Driver Model (IDM), Krauss Model and Das and Asundi were selected for this study. These models were implemented in a microscopic traffic simulation model for a mid-block section. The performance of different vehicle-following models was evaluated based on different Measure of Effectiveness (MoE) using field data collected from a four-lane divided urban arterial road in Chennai city. Speed-concentration and flow-concentration relationships for different vehicle-following models were developed and analyzed for different compositions. Capacity is higher when the proportion of smaller size vehicles is higher, since these vehicles use longitudinal and lateral gaps effectively. The simulation model was also applied to evaluate a range of traffic control measures based on vehicle type and lane (Ex: exclusion of auto-rickshaws, heavy vehicles, auto-rickshaws + heavy vehicles, etc.). The results showed the promise of some measures based on vehicle class, namely, the exclusion of auto rickshaws or auto rickshaws and heavy vehicles. The findings have interesting implications for capacity and PCU estimation and Level of Service (LoS) Analysis.

Characteristics of Mixed Traffic on Urban Arterials with Significant Volumes of Motorized Two-Wheelers: Role of Composition, Intraclass Variability, and Lack of Lane Discipline

Mixed traffic in the cities of many developing countries is characterized by a lack of lane discipline, varying compositions of constituent vehicle types, and significant intraclass variability in static and dynamic characteristics. However, the influence of these factors on traffic flow parameters is not well understood. This study addressed the influence of lane discipline, intraclass variability, and composition on traffic flow characteristics under heterogeneous traffic conditions in Chennai, India. A microscopic traffic simulation model was calibrated and validated with field data from a four-lane divided urban arterial road in Chennai. The preliminary analysis indicated that factors such as composition, intraclass variability, and lane discipline had a statistically significant effect on stream speed. Speed–flow and speed–density relationships were developed on the basis of simulation results. These results showed a clear influence of lack of lane discipline, variability, and composition on stream speed. The influence varied depending on volume level and type of subject vehicle. The effect of composition on capacity was quantified. When two-wheelers had a predominant share, they enjoyed better performance in the absence of lane discipline. However, when cars and heavy vehicles had a significant presence, the impact of the lack of lane discipline was much smaller. The simulation model was applied to evaluate a range of traffic control measures based on vehicle type and lane. The results showed the promise of some measures based on vehicle class, namely, the exclusion of autorickshaws or autorickshaws and heavy vehicles. The findings have interesting implications for efficiency, user experience, and equity in mixed traffic.